1 RUNNING A PROGRAM
1.7 Interrupt Program
81
1
Multiple interrupt function
When a new interrupt triggered by another factor occurs during execution of an interrupt program, the running program will be
suspended if its priority is lower than that of the new interrupt. A program with higher priority is executed based on the set
priority whenever its execution condition is satisfied.
Interrupt priority
If the interrupt priority of a program for which its execution condition has been satisfied is higher than that of the running
program, the programs are executed in accordance with their interrupt priority. If the interrupt priority of the new program is the
same or lower, it enters the waiting status until the running program finishes. The interrupt priorities 1 to 4 listed below cannot
be changed, whereas the interrupt priorities 5 to 8 can. ( Page 82 Interrupt priority setting)
(1) A high-priority interrupt is executed by interrupting a low-priority interrupt.
(2) Even if a high-priority interrupt occurs, it enters the waiting status until the interrupt in execution is completed.
Interrupt
priority
Interrupt factor (Interrupt pointer) Execution sequence at simultaneous
occurrence
Changeability
High
Low
1 High-speed interrupt by internal timer 1 (I49) Unchangeable
(Fixed)
2 High-speed interrupt by internal timer 2 (I48)
3 Inter-module synchronous interrupt (I44), Multiple CPU
synchronous interrupt (I45)
I45 I44
4 Interrupt by internal timer (I28 to I31), Fixed scan execution type
program
I31 I30 I29 I28 Fixed scan execution
type program
5 to 8 Interrupt from module (I0 to I15, I50 to I1023) I0 I1023 Changeable
(1)
(2)
When the multiple interrupt function is enabled
I10 interrupt program
I0 interrupt program
Main routine program
Time
I10 interrupt program
I0 interrupt program
Main routine program
Time
Interrupt is being executed.
Interrupt stops.
interrupt occurs.
Program stops.
Program restarts.
I10: High
I0: Low
When not set (at default)
[Priority]
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